1. Field of the Invention
The present invention relates generally to fuel conditioning systems. More specifically, the present invention relates to fuel conditioning systems for natural gas fuel powered turbines.
2. Description of the Related Art
In the field of natural gas fuel powered turbines, the manufacturers of the turbines put very strict restrictions upon the quality of the fuel that can be used with their turbines. In some countries the fuel, provided from a pipeline supplying the turbine with fuel, does not comply with these restrictions. The fuel from the pipeline is typically at a higher pressure than that needed by the turbine with a tendency for variations in pressure. The fuel may also contain various contaminants such as moisture, liquid hydrocarbons, particulates and other liquids. The manufacturers have restricted the permissible amounts of various contaminants, put limits on other fuel parameters, and put limits on the rate of change of those parameters within the allowed range. The importance of these restrictions is typically found in the warranty provisions for the turbine unit. The manufacturer's warranty for a large natural gas fuel-powered turbine is typically voided, if fuel is used that does not meet the manufacturer's fuel requirements.
As environmental concerns have led turbine manufacturers to maximize their turbine designs to increase efficiency, the requirements for the fuel used in these turbines have also increased. In order to produce the same energy with less pollution, the fuel must be thoroughly conditioned prior to entering the turbine. Impurities should be removed, the pressure of the fuel should be controlled, and the fuel should be heated, to seek to prevent liquids from forming and from entering the combustion area, or combustor section, of the turbine. Furthermore, there must not be rapid changes of the values of any parameter, even within the acceptable ranges. Therefore, not only should the pressure be limited to a restricted range of values, but the maximum rate of change in pressure should also be limited. The same requirements are true for the temperature of the natural gas fuel. By doing so, optimum turbine operation, safety, and emissions performance may be achieved.
Various systems have been proposed to condition the fuel provided from a natural gas pipeline for use in a natural gas fuel powered turbine. In one system the fuel is filtered and then heated. The heater's output is adjusted based upon the saturation temperature of the fuel gas. Another system proposes a pressure relief system that stores pressure values for comparison. This system is intended to control rapid changes in pressure by comparing values over a short period of time. This system is designed to prevent pressure surges that may damage a turbine. None of these prior systems is believed to consistently meet all of the criteria set by turbine manufacturers. These prior systems attempt to deal with only one criteria, not the overall conditioning of the fuel.
It would be advantageous to have a system that could monitor and control all of the important fuel characteristics to properly condition the fuel to meet the demands of each turbine in a set of turbines. It would also be advantageous to have a verification system that could assist the operator in proving that the fuel provided to the turbine was within the parameters specified by the turbine's manufacturer, in order to assist a turbine operator in processing warranty claims.